Pulverizing mill



Sept. 15, 1931. c, PETERS 1,822,999

PULVERIZING MILL Filed Sept. 24, 1930 Patented Sept. 15 1931 UNITEDCLAUDIUS PETERS, 01F HAMBURG, GERMANY PULVERIZING MILL Application filedSeptember 24, 1930, Serial No. 484,011 and in Germany May 10, 1928.

My invention relates to pulverizing mills and more particularly to millsof the type in which the lighter particles of thepulverized material areseparated from the coarser par- 5 ticles by flowing gas.

It is an object of my invention to improve a mill of this type. To thisend I provide a hopper below the mill, and means for supplying gas underpressure to the hopper so that the gas flows in upward direction throughthe mill from the hopper.

In the drawings affixed to this specification and forming part thereof amill embodying my invention is illustrated diagrammatically by way ofexample.

In'the drawings Fig. 1 is a partly sectional elevation showing acomplete plant including a mill according to my invention and itsgas-circulating system.

Fig. 2 is a section on the line IIII in Fig. 1. f

Referring now to the drawings, the mill illustrated by way of example isof the general construction disclosed in U. S. Letters Patent No.1,358,837. In this mill there is a generally circular track. Asparticularly illustrated in the drawings, 17 is the grinding ring of themill, 18 is its yoke, 19 are pushers on the yoke. A rotatablepul'verizing ele ment is associated with the track; thus 1 are the ballswhich are propelled by the pushers 19. Rotation'is imparted to the yoke19 by means of a shaft 20 and a pulley 21. As here shown the circulartrack is adapted to restrain the rotatable pulverizing element radiallysince the grinding ring 17 completely surrounds the balls 1. X

It is understood that I am not limited to this particular type of mill,nor to the means for rotating its yoke.

A substantially horizontal member is disposed below the pulverizingelement and provides openings through which fine materials grinding ring17 which forms the grinding race for the balls 1. It will'be observedthat the ring plate, here illustrated as the screen 14, is adapted torestrain the pulverizing element vertically. It lies between thepulverizing unit an dthe hopper. 12 is a material hopper below thescreen, 13 is a blade at the end of an arm 22 on the boss 23 of the yoke18 which aids in removing the material from the hopper 12, 15 is adischarge pipe at one no side of the hopper, and 24 is a blade valvewhich closes the discharge pipe 15 Without interfering with the outflowof the material therefrom. It will be evident that any convenient formof air-lock inay be used to per- 05 form the function of the blade valve24 without departing from the proper scope of the present invention.

2 is a casing which is secured on top of the grinding ring 17, 25 is acover at the upper to end of the casing, and 8 is an inverted partitionwhich is suspendedfrom the cover 25 and extends into the casing 2, itslower end being frusto-conical. As will appear from Fig. 2 the partition8-is slotted at 26 and 9 are flapsopposite the slots and extendingtangentially with respect to the wall of the partition 8.

4 is a centrifugal fan 6 is its dischar e pipe the lower end of WhlCl'lextends into t e 30 partition 8, and 7 is' an adjustable nozzle at thelower end of the discharge pipe which I together with an opening at thelower end of the frusto-conic'al portion, constitutes a sort ofinjector. 11 is a branchpipe which 35 extends to the hopper 12 from thedischarge pipe 6. 3 is an outflow pipe which is inserted in the cover25, with its lower enlarged end surrounding the discharge'pipe 6 inco-axial relation. 5 is a centrifugal separator to so which the upperend of the outflow pipe 3 is connected, and 16 is the suction pipe ofthe fan 4 which is connected to the. separator 5 at its upper end.

In operation, the air is circulated in the system by the fan 4. Aportion of the air from the delivery pipe 6 is conducted to the hopper12 by the pipe 11, and rises through the screen 14. The hopper 12 is,therefore, also an air supply chamber. Fans 27 are as its cover 25 whereit is admitted'into the partition 8 through the slots 26 while its flowis reversed and deflected tangentially'by the flaps 9, and finally isdelivered to the separator 5 through the overflow pipe 3. The particleswhich are dropped from the mixture collect in the region of thepartition 8 which surrounds the nozzle 7 where hey are entrained by theflow from the discharge pipe 6, and returned to the mill. The down wardflow at the nozzle 7 does not interfere with the upward flow along thewall of the casing as the two flows are a considerable distance apart.The fans 27 by forcing the air away from the axis of the mill generate avacuum in its axial region which assists the injector-like action of thenozzle 7.

Heavy but fine constituents of the material; for instance the sand whichis normally admixed to lignite'are separated by the screen and droppedinto the hopper 12 Where they are agitated by the blade 13, and finallydischarged through the pipe 15, the valve 24 preventing loss of gas. ofpure lignite are entrained by the air from the hopper 12, andfinallydelivered to the separator 5. Coarser particles of lignite are retainedby the screen 14 until they have been ground to a suflicient degree offineness, and are .then also entrained by the gas, as described. v v

By separating sand or other fine and heavy particles not only the purityof thefinal product is improved but also the wear of the mill isreduced. The fan 4 is also pr'otected from wear by being supplied withpurified gas only through its suction pipe 16.

It will appear that the same volume of gas or air flows continuouslythrough the system and is not made up from any outside source. This hasthe advantage that when treating materials which may form explosivemixtures, such as some classes of lignite, 'sulfur and the like, inertgas may be used instead of air and such gas is continuously circulatedin the system without oxygen havin access to it.

stead of providing a branch pipe 11 from the discharge pipe 6 to thehopper 12, I may connect the discharge pipe 6 itself with the hopper inwhich case obviously the nozzle 7 is dispensed with;

' I wish it to be understood that I do not desire to be limited to theexact details of construction shown and described for 0hviousmodifications will occur to a person skilled in the art.

In theclaims afiixed to this specification The fine particles noselection of any particular modificationof the invention is intended tothe exclusion of other modifications thereof and the right tosubsequently make claim to any modification not covered by these claimsis expressly reserved.

I claim: L 1. In a pulverizing mill, a rotatable pulverizing element, agenerally circular track associated therewith, a substantiallyhorizontal member providing openings below said pulverizing elementthrough which fine materials may flow downwardly and through which airmay pass upwardly, a material hopper and air supply chamber beneath saidcircular track, a discharge pipe associated with said hopper, an airlock closing said discharge pipe, but permitting material to passtherethrough and a movable element in said hopper adapted to movematerial therein toward said discharge pipe substantially as described.

2. In a pulverizing mill a pulverizing unit, a casing above saidpulverizing unit, a tubular partition in said casing carried therebywith its open end facing said pulverizing unit, a separator, a pipe lineconnecting said casing to said separator, a fan, a second pipe lineconnecting said separator to the suction side of said fan, a, collectionhopper below said pulverizing unit, a discharge pipe extending from saidfan into said partition so as to form an injector with its open end, anda branch pipe extending from sald discharge pipe to said hopper forcarrying a current of air thereto.

3. In an air discharge pulverizing mill, a

rotatable pulverizing element, a generally.

circular track associated therewith pgsitioned to restrain saidrotatable pulverizing element radially, a substantially horizontal ringplate beneath said rotatable pulverizing element adapted to.restrainsaid pulverizing element vertically, said ring plate having openingstherein for conducting fine materials downwardly and for permitting airto pass upwardly and a collection hopper and a r supply chamber beneathsaid ring plate substantially as described.

4. In an air. discharge pulverizing mill, a rotatable pulverizingelement, a generally circular perpendicular track associated-therewithand a substantially horizontal member supporting said rotatable element;said hori-.

zontal member having perforations therein immediately. beneath saidrotatable element for conducting fine materials downwardly and forpermitting air to pass upwardly to ducting fine materials downwardly andfor means for rotating said pulverizing element permitting air to passupwardly to carry off and said discharge blade substantially as definematerials, a collection hopper and air i supply chamber beneath saidcircular track, a discharge pipe associated with said hopper and an airlock closing said discharge pipe but permitting material to passtherethrough.

6. In a pulverizing mill, a rotatable pulverizing element, a generallycircular track with its race portion substantially vertically arranged,a substantially horizontal perforated member supporting said pulverizingelement, drive means for rotating said pulverizing element in engagementwith said track, an air outlet at the upper portion of the milland anair inlet below said perforated member, means for conducting air underpressure through the mill, a collection hopper below said perforatedmember, and a rotatable blade in said hopper operatively connected withsaid drive means.

7. Ina pulverizing mill, a rotatable pulverizing element, a generallycircular track associated therewith, an air outlet above said rotatablepulverizing element, an air inlet below said rotatable pulverizingelement and a substantially horizontal member support- I ing saidrotatable element, said substantially horizontal member havingperforations therein immediately beneath said rotatable element forconducting fine materials downwardly and for permitting air to passupwardly to carry ofi fine materials.

8. In an air discharge pulverizing mill, a rotatable pulverizingelement, a generally circular track associated therewith positioned torestrain said rotatable pulverizing element radially, a substantiallyhorizontal ring plate beneath said rotatable pulverizing element adaptedto restrain said pulverizing element vertically, said ring plate havingopenings therein immediately beneath said rotatable pulverizing elementfor conducting fine materials downwardly and for permitting air to passupwardly, a member substantially closing the space within said ringplate, and a collection hopper and air supply chamber be neath said ringplate substantially as de scribed.

9. In an air discharge pulverizing mill, a rotatable pulverizingelement, a generally circular track associated therewith positioned torestrain said rotatable pulverizing element radially, a substantiallyhorizontal ring plate beneath said rotatable pulverizing element adaptedto restrain said pulverizing element vertically, said ring. plate havingopenings therein immediately beneath said rotatable pulverizing elementfor conducting fine ma terials downwardly and for permitting air to passupwardly, a collection hopper" and air supply chamber beneath said ringplate, a rotatable discharge blade in said hopper and Int estimonywhereof I aflix m signature.

CLAUDIUS ETERS.

